Soft aluminum on the Ball detent & on the flush cocking system & hammer rention.

Review:

When I first started using the marker, I was instantly impressed by the suppressive firepower it has. Scoring kills it not a problem, and switching it to full auto and dumping at a group is terrifying. But...
Some parts on the gun are made of cheaper materials than I've come to expect.
The ball detent got some swab material in it and was mauled up while removing because it's lok-tited in place and round. (could be fixed by going over to a autococker style detent)
The high velocity of the bolt's movement has caused the soft metal of the flush cocking system to get a uprising that I've had to remove with a dermel. (could be fixed by making it out of steel, not aluminum, or ditch it and tap the back of the bolt for a 10-32 autococker style cocking rod.)
I swapped out all the o-rings upon recieving the marker.
Other than those material issues, the gun has always performed as expectated.
Feed neck has a nice tight fit
I could tell no difference between the Smart Parts Barrel and the OE barrel which looks like a DYE Boom clone.
Withering rates of fire and very reliable.

Conclusion:

Right from the box it's very good. Some things could be improved.
It's excellent for a reliable back-up weapon if you've already got something.

(I always shoot my pump sniper and take out the guys with the Bob Longs..., but I know when to grab the full-auto and make my competition pee thier pants.)